S
M
T
W
T
F
S
29
39°
29°
30
47°
34°
1
41°
35°
2
41°
35°
3
45°
34°
4
40°
34°
5
46°
33°
6
50°
34°
7
45°
31°
8
41°
30°
9
40°
29°
10
40°
27°
11
48°
22°
12
43°
18°
13
35°
14°
14
34°
20°
15
33°
15°
16
35°
27°
17
37°
28°
18
39°
27°
19
41°
28°
20
42°
28°
21
42°
27°
22
41°
28°
23
47°
21°
24
46°
14°
25
38°
13°
26
30°
16°
27
33°
25°
28
34°
26°
29
44°
28°
30
45°
32°
31
48°
31°
1
49°
18°
2
48°
13°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
December Weather in Sumner
Sumner's December 2026 forecast shows daily high temperatures ranging from 30° to 50°, with overnight lows between 13° and 35°. The average high for December is 41° with an average low of 26°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how December weather will actually feel in Sumner. See also: January | February | March.